U.S. patent number 9,250,204 [Application Number 14/604,959] was granted by the patent office on 2016-02-02 for graphene sensor.
This patent grant is currently assigned to International Business Machines Corporation. The grantee listed for this patent is International Business Machines Corporation. Invention is credited to Dechao Guo, Shu-Jen Han, Chung-Hsun Lin, Ning Su.
United States Patent |
9,250,204 |
Guo , et al. |
February 2, 2016 |
Graphene sensor
Abstract
A method for forming a sensor includes forming a channel in
substrate, forming a sacrificial layer in the channel, forming a
sensor having a first dielectric layer disposed on the substrate, a
graphene layer disposed on the first dielectric layer, and a second
dielectric layer disposed on the graphene layer, a source region, a
drain region, and a gate region, wherein the gate region is
disposed on the sacrificial layer removing the sacrificial layer
from the channel.
Inventors: |
Guo; Dechao (Wappingers Falls,
NY), Han; Shu-Jen (Cortlandt Manor, NY), Lin;
Chung-Hsun (White Plains, NY), Su; Ning (Fishkill,
NY) |
Applicant: |
Name |
City |
State |
Country |
Type |
International Business Machines Corporation |
Armonk |
NY |
US |
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Assignee: |
International Business Machines
Corporation (Armonk, NY)
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Family
ID: |
44646519 |
Appl.
No.: |
14/604,959 |
Filed: |
January 26, 2015 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20150137078 A1 |
May 21, 2015 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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13605107 |
Sep 6, 2012 |
9068936 |
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12727434 |
Mar 19, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L
51/0048 (20130101); H01L 29/1606 (20130101); G01N
27/4145 (20130101); H01L 29/42384 (20130101); G01N
27/4146 (20130101); H01L 29/78684 (20130101); H01L
29/4908 (20130101); H01L 29/66742 (20130101) |
Current International
Class: |
H01L
29/786 (20060101); H01L 51/00 (20060101); H01L
29/49 (20060101); H01L 29/66 (20060101); H01L
29/16 (20060101); G01N 27/414 (20060101); H01L
21/336 (20060101); H01L 29/423 (20060101) |
Field of
Search: |
;257/24,E21.409,E29.273
;438/49 ;977/734,742,774,938 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Caldwell, J.D. et al., "Technique for the Dry Transfer of Epitaxial
Graphene onto Arbitrary Substrates," ACSNANO, vol. 4, No. 2, Jan.
25, 2010, pp. 1108-1114. cited by applicant.
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Primary Examiner: Gurley; Lynne
Assistant Examiner: Webb; Vernon P
Attorney, Agent or Firm: Cantor Colburn LLP Alexanian;
Vazken
Parent Case Text
DOMESTIC PRIORITY
This application is a divisional of U.S. patent application Ser.
No. 13/605,107, filed Sep. 6, 2012, now U.S. Pat. No. 9,068,936,
which is a continuation application of U.S. patent application Ser.
No. 12/727,434, filed on Mar. 19, 2010, now abandoned, the
disclosure of which is incorporated by reference herein in its
entirety.
Claims
What is claimed is:
1. A sensor, comprising: a fluid channel defined in a substrate,
the fluid channel having a first end and a second end; a first
cavity in communication with the first end of the fluid channel,
and a second cavity in communication with the second end of the
fluid channel opposite the first end so as to define a fluid flow
path comprising the first cavity, the fluid channel and the second
cavity; a transistor gate dielectric layer, comprising a first
dielectric layer, disposed on the substrate and over the fluid
channel; a graphene layer disposed on the transistor gate
dielectric layer; a second dielectric layer disposed on the
graphene layer; a source region disposed on the transistor gate
dielectric layer, the source region also in contact with a first
end of the graphene layer; a drain region disposed on the gate
dielectric layer, the drain region also in contact with a second
end of the graphene layer; a capping layer disposed on a portion of
the substrate; and wherein the channel comprises a physical opening
formed in the substrate so as to define a gap between a bottom
surface of the gate dielectric layer and a top surface of the
substrate.
2. The sensor of claim 1, wherein the sensor includes a gate
region.
3. The sensor of claim 1, wherein the graphene layer includes a
graphene tube.
4. The sensor of claim 1, wherein the second dielectric layer has a
greater thickness than the first dielectric layer.
5. The sensor of claim 1, wherein a longitudinal axis of the
channel is orthogonal to an axis that connects the source and drain
regions.
Description
FIELD OF INVENTION
The present invention relates to sensors, and particularly graphene
biosensors.
DESCRIPTION OF RELATED ART
Biosensors may be used in life sciences, clinical diagnostics, and
medical research for affinity based sensing. Such as, for example,
hybridization between complementary single strand DNA in microarray
or affinity binding of a matched antibody-antigen pair.
Biosensors may include a biological recognition element and a
transducer that converts a recognition event into a measurable
electronic signal.
BRIEF SUMMARY
In one aspect of the present invention, a method for forming a
sensor includes forming a channel in substrate, forming a
sacrificial layer in the channel, forming a sensor having a first
dielectric layer disposed on the substrate, a graphene layer
disposed on the first dielectric layer, and a second dielectric
layer disposed on the graphene layer, a source region, a drain
region, and a gate region, wherein the gate region is disposed on
the sacrificial layer removing the sacrificial layer from the
channel.
In another aspect of the present invention, a method for forming a
sensor includes forming a channel substrate, forming a sacrificial
layer in the channel, forming a first dielectric layer on the
substrate and the sacrificial layer, forming a graphene layer on
the first dielectric layer, forming a second dielectric layer on
the graphene layer, removing portions of the second dielectric
layer and portions of the graphene layer to expose a first portion
of the first dielectric layer and a second portion of the first
dielectric layer, forming a source region on the exposed first
portion of the first dielectric layer and drain region on the
second portion of the first dielectric layer, forming a capping
layer on the exposed substrate, graphene layer, source region,
drain region, and second dielectric layer, removing portions of the
capping layer to expose the source region, drain region, the second
dielectric layer, and portions of the sacrificial layer, and
removing the sacrificial layer from the channel.
Additional features and advantages are realized through the
techniques of the present invention. Other embodiments and aspects
of the invention are described in detail herein and are considered
a part of the claimed invention. For a better understanding of the
invention with the advantages and the features, refer to the
description and to the drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
The subject matter which is regarded as the invention is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The forgoing and other
features, and advantages of the invention are apparent from the
following detailed description taken in conjunction with the
accompanying drawings in which:
FIGS. 1-6B illustrate an exemplary method for forming a graphene
sensor.
DETAILED DESCRIPTION
FIGS. 1-6B illustrate an exemplary method for forming a graphene
sensor. FIG. 1 illustrates a side view of a channel 102 formed in a
substrate 100. The substrate 100 may be, for example, a silicon
substrate or a buried oxide (BOX) substrate. The channel 102 may be
formed by, for example, a lithographic patterning and etching
process.
FIG. 2A illustrates a side view of the resultant structure
following the deposition of a sacrificial layer 202 in the channel
102 (of FIG. 1). The sacrificial layer 202 may include for example,
SiGe, Ge, materials. FIG. 2B illustrates a top-down view of the
substrate 100 and sacrificial layers 202. Though the illustrated
embodiment of FIG. 2B includes two sacrificial layer 202 regions,
alternate embodiments may include any number of sacrificial layer
202 regions.
FIG. 3 illustrates a side view of the resultant structure following
the deposition of a first dielectric layer 302 on the substrate 100
and the sacrificial layer 202; a graphene layer 304 on the first
dielectric layer 302; and a second dielectric layer 306 on the
graphene layer 304. The first dielectric layer 302 may include an
insulating material such as, for example, SiO.sub.2, HfO.sub.2,
Si.sub.3N.sub.4, HfO.sub.2, ZrO.sub.2, Ta.sub.2O.sub.5, TiO.sub.2,
or their mixtures, materials. The graphene layer 304 may include a
graphene material such as, for example, a graphene tube The second
dielectric layer 306 may include dielectric materials such as, for
example, HfO.sub.2 or Si.sub.3N.sub.4. In the illustrated
embodiment, the thickness (x') of second dielectric layer 306 is
greater than the thickness (x) of the first dielectric layer
302.
The graphene layer 304 may be formed by, for example, depositing a
graphene material on the first dielectric layer 302, and a layer of
thermal release tape (not shown) on the graphene material. A
variety of thermal and mechanical processes are used to bond the
graphene material to the first dielectric layer 302. The tape may
be removed along with layers of the graphene material. The
resultant structure includes a thin layer of graphene material
(graphene layer 304) bonded to the first dielectric layer.
FIG. 4 illustrates the resultant structure following the removal of
portions of the second dielectric layer 306 and portions of the
graphene layer 304 that exposes portions of the graphene layer 304
and portions of the first dielectric layer 302. Source region (S)
402 and drain regions (D) 404 are formed on exposed portions of the
first dielectric layer 302. The source and drain regions 402 and
404 are formed by, for example, direct metal deposition followed by
thermal annealing to form an ohmic contact. The metal materials may
include, for example, Ti, Au, W, Ag, or Ta.
FIG. 5 illustrates the resultant structure following the deposition
of a capping layer 502 on the exposed portions of the substrate
100, the sacrificial layer 202, the graphene layer 304, the source
region 402, the drain region 404, and the second dielectric layer
306. In the illustrated embodiment, the thickness of the capping
layer 502 has been reduced by, for example, a chemical mechanical
polishing (CMP) or other suitable process, to expose the second
dielectric layer 306. Cavities 504 and 506 may be formed by, for
example, a lithographic etching process to expose the source and
drain regions 402 and 404.
FIG. 6A illustrates the resultant structure following the removal
of the sacrificial layer 202 (of FIG. 5) from the channel 102. FIG.
6B illustrates a top-down partially cut-away view of the resultant
structure. Referring to FIG. 6B, the sacrificial layer 202 may be
removed by removing portions of the capping layer 502 to form
cavities 602 and 604 that expose opposing distal ends of the
sacrificial layer 202. The cavities 602 and 604 may be formed by,
for example, a lithographic etching process. Once the cavities 602
and 604 are formed, the sacrificial layer 202 may be removed by,
for example, a selective isotropic etching process that removes the
exposed sacrificial layer 202 material. The removal of the
sacrificial layer 202 from the channel 102 forms a flow path
indicated by the arrow 601. The flow path 601 enters the cavity 602
defined by the capping layer 502 and a first distal end of the
channel 102. The flow path 601 runs under the first dielectric
layer 302 (of FIG. 6A) and the capping layer 502 where the flow
path 601 exits from the second cavity 604 defined by a second
distal end of the channel 102 and the capping layer 502. The
illustrated embodiment of FIG. 6B shows a number of devices
arranged with longitudinal axis (y) orthogonal to the longitudinal
axis (z) of the channel the channel 102.
In exemplary operation, a fluid having, for example single strand
DNA flows through the flow path 601 (of FIG. 6B), and the
resistance of the device is measured. Since different types of
single strand DNA may change the measured resistance of the device
(e.g., an increase or a decrease in resistance) the change in
resistance of the device may indicate a type of DNA that is in the
fluid. A fixed voltage bias is applied between the source and drain
regions and the current is monitored. The resistance of the device
is calculated by dividing the voltage by the measured current. When
different types of DNA contact the gate dielectric layer 302, the
transistor may be turned on or off. The resistance of the device
reflects the change in state.
Referring to FIG. 6A, the relatively thin first dielectric layer
302, between the fluid in the flow path 601 (of FIG. 6B) and the
graphene layer 304, improves the sensitivity of the device. Forming
the first dielectric layer 302 on the substrate 100 allows (and
sacrificial layer 202, prior to the removal of the sacrificial
layer 202) the first dielectric layer 302 to be easily formed to a
desired thickness. A relatively thin second dielectric layer 306
may be more difficult to precisely form on the graphene layer 304
due to the material properties of graphene. Forming the fluid flow
path 601 such that the fluid contacts the thinner first dielectric
layer 302, rather than the thicker second dielectric layer 306,
maintains the desired sensitivity of the device.
The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one ore more other features, integers,
steps, operations, element components, and/or groups thereof.
The corresponding structures, materials, acts, and equivalents of
all means or step plus function elements in the claims below are
intended to include any structure, material, or act for performing
the function in combination with other claimed elements as
specifically claimed. The description of the present invention has
been presented for purposes of illustration and description, but is
not intended to be exhaustive or limited to the invention in the
form disclosed. Many modifications and variations will be apparent
to those of ordinary skill in the art without departing from the
scope and spirit of the invention. The embodiment was chosen and
described in order to best explain the principles of the invention
and the practical application, and to enable others of ordinary
skill in the art to understand the invention for various
embodiments with various modifications as are suited to the
particular use contemplated.
The diagrams depicted herein are just one example. There may be
many variations to this diagram or the steps (or operations)
described therein without departing from the spirit of the
invention. For instance, the steps may be performed in a differing
order or steps may be added, deleted or modified. All of these
variations are considered a part of the claimed invention.
While the preferred embodiment to the invention had been described,
it will be understood that those skilled in the art, both now and
in the future, may make various improvements and enhancements which
fall within the scope of the claims which follow. These claims
should be construed to maintain the proper protection for the
invention first described.
* * * * *